At the end of each semester, I take time to review my bible study from the past semester. It is a bit time-consuming since most of the time I'm struggling to decipher my handwriting. Yet it is spiritual encouraging. For me, its like getting a dose of encouragement. I'm able to see how God has worked through my life in ways I was not expecting him to be working. Also, it is a good reminder of how I failed, like forgetting to fulfill certain applications I've made.
My Dad does a yearly review of his bible study, but I've found a three quarter system to work well. It lightens the workload that comes with reviewing my bible study. Though the process of going through past studies is time-consuming it is encouraging and exhorting. Bible study notebooks exist for a reason so we can review what we have written down.